U.S. patent number 6,135,940 [Application Number 09/210,332] was granted by the patent office on 2000-10-24 for centrifugally activated tube rotator mechanism and method for using the same.
This patent grant is currently assigned to Becton, Dickinson and Company. Invention is credited to Michael R. Walters.
United States Patent |
6,135,940 |
Walters |
October 24, 2000 |
Centrifugally activated tube rotator mechanism and method for using
the same
Abstract
An apparatus is disclosed for use in a centrifuge apparatus to
rotate a fluid tube about its longitudinal axis while the rotor of
the centrifuge apparatus is rotating the fluid tube in a rotational
direction transverse to the longitudinal axis of the tube. The
apparatus comprises a cam which is mechanically coupled to the
fluid tube, and a cam follower configured to apply a driving force
to the cam to cause the cam to rotate, which in turn rotates the
fluid tube about its longitudinal axis. The cam follower applies
the driving force to the cam in response to changes in the
magnitude of centrifugal force applied to the cam follower caused
by increases and decreases in the speed of rotation of the rotor.
The centrifuge apparatus can therefore obtain optical readings of
the centrifuged sample from different locations about the
circumference of the fluid tube.
Inventors: |
Walters; Michael R. (Baltimore,
MD) |
Assignee: |
Becton, Dickinson and Company
(Franklin Lakes, NJ)
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Family
ID: |
27488057 |
Appl.
No.: |
09/210,332 |
Filed: |
December 11, 1998 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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032931 |
Mar 2, 1998 |
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918437 |
Aug 26, 1997 |
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918473 |
Aug 26, 1997 |
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721782 |
Sep 25, 1996 |
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Current U.S.
Class: |
494/19;
494/37 |
Current CPC
Class: |
B04B
5/02 (20130101); B04B 5/0414 (20130101) |
Current International
Class: |
B04B
5/02 (20060101); B04B 5/04 (20060101); B04B
5/00 (20060101); B04B 007/00 () |
Field of
Search: |
;494/1,11,16,19,20,31,33,37,47 ;366/217 ;422/72 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Cooley; Charles E.
Attorney, Agent or Firm: Weintraub, Esq.; Bruce S.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This is a continuation-in-part application of U.S. patent
application Ser. No. 09/032,931, filed on Mar. 2, 1998, and of U.S.
patent application Ser. Nos. 08/918,437 and 08/918,473, both filed
on Aug. 26, 1997, now abandoned, as continuations-in-part of U.S.
patent application Ser. No. 08/721,782, filed on Sep. 25, 1996, now
abandoned. The entire contents of each of of the foregoing U.S.
patent applications is expressly incorporated herein by
reference.
Related subject matter is disclosed in a U.S. patent application of
Stephen C. Wardlaw entitled "Assembly for Rapid Measurement of Cell
Layers", Ser. No. 08/814,536, filed on Mar. 10, 1997 which has
issued as U.S. Pat. No. 5,889,584; in a U.S. patent application of
Stephen C. Wardlaw entitled "Method for Rapid Measurement of Cell
Layers", Ser. No. 08/814,535, filed on Mar. 10, 1997 which has
issued as U.S. Pat. No. 5,888,184; in a U.S. patent application of
Edward G. King, Michael A. Kelly, Bradley S. Thomas and Michael R.
Walters entitled "Disposable Blood Tube Holder and Method for Using
the Same", Ser. No. 09/033,373, filed on Mar. 2, 1998; in a U.S.
patent application of Bradley S. Thomas, Michael A. Kelly, Michael
R. Walters, Edward M. Skevington and Paul F. Gaidis entitled "Blood
Centrifugation Device with Movable Optical Reader", Ser. No.
09/033,368, filed on Mar. 2, 1998; and in a U.S. patent application
of Bradley S. Thomas, entitled "Flash Tube Reflector With Arc
Guide", Ser. No. 09/032,935, filed on Mar. 2, 1998, which issued as
U.S. Pat. No. 6,030,086 all of said applications being expressly
incorporated herein by reference.
Claims
What is claimed is:
1. An indexing apparatus, adaptable for use in a rotor of a
centrifuge apparatus, to rotate a fluid tube about a rotational
axis which is in substantial alignment with the longitudinal axis
of the tube, the rotor being adapted to rotate the fluid tube in a
rotational direction transverse to the longitudinal axis of the
tube, the indexing apparatus comprising:
a rotatable member which is mechanically coupled to the fluid tube;
and
a driver, adapted to generate a driving force in response to a
variation in a speed of rotation at which the rotor rotates the
fluid tube in the rotational direction, and to apply the driving
force to the rotatable member to control the rotatable member to
rotate the fluid tube about the rotational axis, while the rotor is
rotating the fluid tube in the rotational direction.
2. An apparatus as claimed in claim 1, wherein:
the rotatable member comprises a cam having a groove therein, and
the driver comprises a cam follower which moves in the groove to
engage and rotate the cam to rotate the fluid tube.
3. An apparatus as claimed in claim 2, wherein:
the cam defines the groove as a groove pattern disposed in a
surface of the cam; and
the groove pattern permits the cam follower to rotate the cam in a
first rotational direction, and prevents the cam follower from
rotating the cam in a second rotational direction opposite the
first rotational direction.
4. An apparatus as claimed in claim 1, wherein:
the driver applies the driving force to the rotatable member to
cause the rotatable member to rotate the fluid tube in increments
defined by the rotatable member.
5. An apparatus as claimed in claim 1, wherein:
the rotatable member comprises a cam having a groove pattern
therein; and
the driver comprises a block and a cam follower which is coupled to
the block and engages the groove pattern in the cam;
the block being movable along a direction transverse to a direction
radial of the cam, such that the cam follower engages the groove
pattern in the cam and rotates the cam when the block moves along
the transverse direction.
6. An indexing apparatus, adaptable for use in a rotor of a
centrifuge apparatus, to rotate a fluid tube about a rotational
axis which is in substantial alignment with the longitudinal axis
of the tube, comprising:
a rotatable member which is mechanically coupled to the fluid tube;
and
a driver, adapted to convert a centrifugal force generated by
rotation of the rotor into a driving force, and to apply the
driving force to the rotatable member to control the rotatable
member to rotate the fluid tube about the rotational axis, while
the rotor is rotating the fluid tube in a rotational direction
transverse to the longitudinal axis of the tube.
7. An indexing apparatus, adaptable for use in a rotor of a
centrifuge apparatus, to rotate a fluid tube about a rotational
axis which is in substantial alignment with the longitudinal axis
of the tube, comprising:
a rotatable member which is mechanically coupled to the fluid tube
and comprises a cam having a groove pattern therein;
a driver, adapted to apply a driving force to the rotatable member
to control the rotatable member to rotate the fluid tube about the
rotational axis, while the rotor is rotating the fluid tube in a
rotational direction transverse to the longitudinal axis of the
tube, the driver comprising a block and a cam follower, which is
coupled to the block and engages with the groove pattern in the
cam, the block being movable along a direction transverse to a
direction radial of the cam, such that the cam follower engages the
groove pattern in the cam and rotates the cam when the block moves
along the transverse direction; and
an urging device which applies an urging force to the block to urge
the block in a first direction along the transverse direction;
and
wherein the block is adapted to be urged in a second direction,
substantially opposite the first direction, by centrifugal force
generated by rotation of the rotor, and moves along the second
direction when a magnitude of the centrifugal force is greater than
a magnitude of the urging force.
8. An apparatus as claimed in claim 7, wherein:
the urging device comprises at least one spring.
9. A system for centrifuging fluid stored in a fluid tube,
comprising:
a rotor, adapted to rotate the fluid tube in a rotational direction
transverse to the longitudinal axis of the fluid tube; and
an indexing device which, in response to a variation in a speed of
rotation at which the rotor rotates the fluid tube in the
rotational direction, rotates the fluid tube about a rotational
axis which is in substantial alignment with the longitudinal axis
of the tube while the rotor is rotating the fluid tube in the
rotational direction.
10. A system as claimed in claim 9, wherein the indexing device
further comprises:
a rotatable member which is mechanically coupled to the fluid tube;
and
a driver, adapted to apply a driving force to the rotatable member
to rotate the fluid tube about the rotational axis, when the rotor
is rotating the fluid tube in the rotational direction.
11. A system as claimed in claim 10, wherein:
the driver applies the driving force to the rotatable member to
cause the rotatable member to rotate the fluid tube in increments
defined by the rotatable member.
12. A system as claimed in claim 10, wherein:
the rotatable member is a cam having a groove therein, and the
driver is a cam follower which moves in the groove to engage and
rotate the cam to rotate the fluid tube.
13. A system for centrifuging fluid stored in a fluid tube,
comprising:
a rotor, adapted to rotate the fluid tube in a rotational direction
transverse to the longitudinal axis of the fluid tube; and
an indexing device, adapted to rotate the fluid tube about a
rotational axis which is in substantial alignment with the
longitudinal axis of the tube while the rotor is rotating the fluid
tube in the rotational direction, wherein the indexing device
comprises:
a rotatable member which is mechanically coupled to the fluid tube;
and
a driver, adapted to convert a centrifugal force generated by
rotation of the rotor into a driving force which drives the
rotatable member to rotate the fluid tube about the rotational axis
while the rotor is rotating the fluid tube in the rotational
direction.
14. A method for centrifuging fluid stored in a fluid tube,
comprising the steps of:
rotating the fluid tube in a rotational direction transverse to the
longitudinal axis of the fluid tube;
varying a speed of rotation of the fluid tube in the transverse
rotational direction to generate a driving force; and
applying the driving force to the fluid tube to rotate the fluid
tube about a rotational axis which is in substantial alignment with
the longitudinal axis of the fluid tube while the fluid tube is
being rotated in the rotational direction.
15. A method as claimed in claim 14, wherein the applying step
comprises the step of:
rotating a rotatable member, which is mechanically coupled to the
fluid tube, to rotate the fluid tube about the rotational axis.
16. A method as claimed in claim 14, further comprising the step
of:
placing the tube in a rotor; and
wherein the transverse rotational direction rotating step comprises
the step of rotating the rotor.
17. A method as claimed in claim 14, wherein:
the rotational axis rotating, step comprises the steps of rotating
the fluid tube about the rotational axis incrementally.
18. A method as claimed in claim 14, wherein:
the rotational axis rotating step permits rotation of the fluid
tube in a first rotational direction about the rotational axis
while preventing rotation of the fluid tube in a second rotational
direction, opposite the first rotational direction, about the
rotational axis.
19. A method for centrifuging fluid stored in a fluid tube,
comprising the steps of:
placing the tube in a rotor;
rotating the rotor to rotate the fluid tube in a rotational
direction transverse to the longitudinal axis of the fluid tube;
and
converting centrifugal force generated by rotation of the rotor
into rotational force which rotates the fluid tube about a
rotational axis which is in substantial alignment with the
longitudinal axis of the tube while the fluid tube is being rotated
in the rotational direction.
Description
BACKGROUND OF THE INVENTION
The present invention relates generally to a device, preferably for
use in a blood centrifuge apparatus, which rotates a fluid tube
about its longitudinal axis while the fluid tube is being rotated
by the centrifuge apparatus. More particularly, the present
invention relates to a device which is coupled to the rotor of a
blood centrifuge apparatus, and which is actuated by centrifugal
force generated by rotation of the centrifuge rotor to rotate a
blood tube carried by the rotor about an axis substantially
corresponding to the longitudinal axis of the blood tube, while the
rotor is spinning the blood tube, so that successive images of the
centrifuged blood can be obtained from different locations about
the circumference of the blood tube.
As part of a routine physical or diagnostic examination of a
patient, it is common for a physician to order a complete blood
count for the patient. The patient's blood sample may be collected
in one of two ways. In the venous method, a syringe is used to
collect a sample of the patient's blood in a test tube containing
an anticoagulation agent. A portion of the sample is later
transferred to a narrow glass capillary tube, known as a fluid tube
or blood tube. The open end of the fluid tube is placed in the
blood sample in the test tube, and a quantity of blood enters the
fluid tube by capillary action. In the capillary method, the
syringe and test tube are not used and the patient's blood is
introduced directly into fluid tube from a small incision or
puncture made in the skin. In either case, the fluid tube is then
placed in a centrifuge, such as the Model 424740 centrifuge
manufactured by Becton Dickinson and Company.
In the centrifuge, the fluid tube containing the blood sample is
rotated at a desired speed (typically 8,000 to 12,000 rpm) for
several minutes. The high speed centrifugation separates the
components of the blood by density. Specifically, the blood sample
is divided into a layer of red blood cells, a buffy coat region
consisting of layers of granulocytes, mixed lymphocytes and
monocytes, and platelets, and a plasma layer. The length of each
layer can then be optically measured, either manually or
automatically, to obtain a count for each blood component in the
blood sample. This is possible because the inner diameter of the
fluid tube and the packing density of each blood component are
known, and hence the volume occupied by each layer and the number
of cells contained within it can be calculated based on the
measured length of the layer. Exemplary measuring devices that can
be used for this purpose include those described in U.S. Pat. Nos.
4,156,570 and 4,558,947, both to Stephen C. Wardlaw, and the
QBC.RTM. "AUTOREAD" hematology system manufactured by Becton
Dickinson and Company.
Several techniques have been developed for increasing the accuracy
with which the various layer thickness in the centrifuged blood
sample can be determined. For example, because the buffy coat
region is typically small in comparison to the red blood cell and
plasma regions, it is desirable to expand the length of the buffy
coat region so that more accurate measurements of the layers in
that region can be made. As described in U.S. Pat. Nos. 4,027,660,
4,077,396, 4,082,085 and 4,567,754, all to Stephen C. Wardlaw et
al., and in U.S. Pat. No. 4,823,624, to Rodolfo R. Rodriguez et
al., this can be achieved by inserting a precision-molded plastic
float into the blood sample in the fluid tube prior to
centrifugation. The float has approximately the same density as the
cells in the buffy coat region, and thus becomes suspended in that
region after centrifugation. Since the outer diameter of the float
is only slightly less than the inner diameter of the fluid tube
(typically by about 80 .mu.m), the length of the buffy coat region
will expand to make up for the significant reduction in the
effective diameter of the tube that the buffy coat region can
occupy due to the presence of the float. By this method, an
expansion of the length of the buffy coat region by a factor
between 4 and 20 can be obtained. The cell counts calculated for
the components of the buffy coat region will take into account the
expansion factor attributable to the float.
Another technique that is used to enhance the accuracy of the layer
thickness measurements is the introduction of fluorescent dyes (in
the form of dried coatings) into the fluid tube. When the blood
sample is added to the fluid tube, these dyes dissolve into the
sample and cause the various blood cell layers to fluoresce at
different optical wavelengths when they are excited by a suitable
light source. As a result, the boundaries between the layers can be
discerned more easily when the layer thicknesses are measured
following centrifugation.
Typically, the centrifugation step and the layer thickness
measurement step are carried out at different times and in
different devices. That is, the centrifugation operation is first
carried out to completion in a centrifuge, and the fluid tube is
then removed from the centrifuge and placed in a separate reading
device so that the blood cell layer thicknesses can be measured.
This added step of removing the blood tube from the centrifuge
device increases the time needed to complete the layer reading
process. Furthermore, because the tubes must be handled and moved
between the centrifuging device and layer reading device, the
likelihood that damage to the tubes will occur is increased.
Additionally, because the centrifuging operation is stopped when
the blood tube is being moved from the centrifuge device to the
layer reading device, the blood components that have been compacted
into their individual layers due to the centrifugation may begin to
migrate into adjacent layers, thus resulting in inaccurate
readings. Also, since the centrifuge can "spin down" multiple fluid
tubes, the manual transfer to the reading device increases the
chance of sample identification error.
More recently, a technique has been developed in which the layer
thicknesses are calculated using a dynamic or predictive method
while centrifugation is taking place. This is advantageous not only
in reducing the total amount of time required for a complete blood
count to be obtained, but also in allowing the entire procedure to
be carried out in a single device. Apparatus and methods for
implementing this technique are disclosed in the copending
applications mentioned previously in the section entitled
"Cross-Reference to Related Applications".
In order to allow the centrifugation and layer thickness
measurement steps to be carried out simultaneously, it is necessary
to "freeze" the image of the sample tube as it rotates at high
speed on the centrifuge rotor. This can be accomplished by means of
a xenon flash lamp assembly that produces an intense excitation
pulse of light energy once per revolution of the centrifuge rotor.
The pulse of light excites the dyes in the expanded buffy coat area
of the sample tube, causing the dyes to fluoresce with light of
known wavelengths. The emitted fluorescent light resulting from the
excitation flash is focused by a high-resolution lens onto a linear
array of charge-coupled devices (CCDs). The CCD array is located
behind a bandpass filter which selects the specific wavelength of
emitted light to be imaged onto the CCD array.
The xenon flash lamp assembly is one of two sources that are used
to illuminate the fluid tube while the centrifuge rotor is in
motion. The other source is an array of light-emitting diodes
(LEDs) which transmit red light through the fluid tube for
detection by the CCD array through a second bandpass filter. The
purpose of the transmitted light is to locate the beginning and end
of the plastic float (and hence the location of the expanded buffy
coat area), and the fill lines of the fluid tube. Further details
of the optical reading apparatus may be found in the aforementioned
copending application of Bradley S. Thomas et al. entitled "Blood
Centrifuge Device with Movable Optical Reader", Ser. No. 09/032,935
which issued as U.S. Pat. 6,030,086.
In order to obtain an accurate measurement of the lengths of the
blood component layers, it is desirable to take several readings
about the circumference of the tube. That is because, when the
blood is centrifuged so that layers of the blood components are
formed in the tube, it is likely that the lengths of the layers
will not be uniform along the entire inner circumference of the
tube. Rather, it is common for a layer to have a longer length on
one side of the tube and a shorter length on the other side.
Because the cell count calculations are based on the measured
lengths of the layers, if the measurements are taken from only one
side of the tube, it is likely that inaccurate cell counts will be
calculated.
Accordingly, it is desirable to rotate the tube of centrifuged
blood so that readings can be taken at various locations (e.g., 8
different locations) about the circumference of the tube. The
respective readings for each layer are then averaged, so that an
average length is computed for each layer. The average length for
each layer is used to calculate the cell count for each respective
blood component in the centrifuged blood sample, thus providing
more accurate cell counts.
It is even more desirable to rotate the tube of centrifuged blood
about its longitudinal axis while the tube remains in the
ccentrifuge rotor, so that the readings can be taken at the various
locations about the circumference of the tube without having to
stop centrifugation and remove the tube from the rotor. Because no
time is lost is transporting the tube of centrifuged blood from the
rotor to the reading device, the overall reading time is reduced.
Moreover, because less handling of the tube is required, the
likelihood of damaging or misidentifying the fluid tube is also
minimized.
A continuing need therefore exists for an apparatus which is
capable of centrifuging a blood sample stored in a capillary tube
and taking accurate measurements of the component layers of the
centrifuged blood sample while allowing the capillary tube to
remain in the centrifuge device. The present invention is directed
to that objective.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a tube rotating
apparatus which is used in a centrifuge device to rotate a
capillary tube, in which a blood sample being centrifuged is
contained, incrementally about an axis substantially aligned with
the longitudinal axis of the capillary tube, to enable the lengths
of layers of the components in the centrifuged blood sample to be
accurately measured without removing the capillary tube from the
centrifuge apparatus.
Another object of the invention is to provide a tube rotating
apparatus as described above whose rotating of the capillary tube
is controlled by movement of the rotor of the centrifuge device
relative to the tube rotating apparatus, thus providing a tube
rotating apparatus which is simple in operation.
These and other objects of the invention are substantially achieved
by providing a tube rotating apparatus, adaptable for use with a
rotor of a centrifuge device, and which rotates a fluid tube, such
as a capillary tube for collecting a blood sample, about a
rotational axis which is in substantial alignment with the
longitudinal axis of the tube while the rotor of the centrifuge
device is rotating the capillary tube in a centrifuging direction.
The rotating apparatus comprises a cam which is mechanically
coupled to the fluid tube, and a cam follower which applies a
driving force to the cam to rotate the cam, thus rotating the fluid
tube about the rotational axis, while the centrifuge apparatus is
rotating the fluid tube in a centrifuging direction.
The cam includes a plurality of grooves about its outer
circumference which define a plurality of rotational intervals, for
example, eight rotational intervals of 45.degree. each, at which
the cam is rotated by the cam follower. The cam follower can
include a block assembly which is movably coupled to the rotor in a
direction radial of the rotor, and urged toward a first radial
position by an urging member, such as a plurality of springs or the
like. When the rotational speed of the rotor is increased such that
a centrifugal force is imposed on the block assembly which is
sufficient to overcome the urging force imposed on the block
assembly by the urging member, the centrifugal force moves the
block assembly radially of the rotor to a second radial position.
In doing so, the cam follower engages a groove in the cam, and thus
applies a driving force to rotate the cam by one-half of a
rotational interval, which in turn rotates the fluid tube about its
rotational axis by one-half of a rotational interval.
When the rotational speed of the rotor is then decreased, the
centrifugal force imposed on the block assembly decreases to a
magnitude at which the urging member can urge the block assembly
back to the first radial position. In doing so, the cam follower
engages a groove in the cam, and applies a driving force to rotate
the cam by another one-half of a rotational interval. Hence, by
increasing and decreasing the rotational speed of the rotor to move
the block assembly from the first radial position to the second
radial position, and back again to the first radial position, the
cam driver rotates the cam and fluid tube by one rotational
interval.
A reading or multiple readings of the centrifuged sample in the
fluid tube can then be taken, and the process can be repeated to
rotate the cam and fluid tube by another rotational interval. The
process of rotating the cam and fluid tube can be repeated, with a
reading or multiple readings of the centrifuged sample in the fluid
tube being taken at every rotational interval, until the cam and
fluid tube have been rotated through a full rotation, or by any
desired number of rotational intervals.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects, advantages and novel features of the
invention will be more readily appreciated from the following
detailed description when read in conjunction with the accompanying
drawings, in which:
FIG. 1 is a top plan view of a blood centrifuge rotor assembly in
which a tube rotating apparatus according to an embodiment of the
present invention is employed;
FIG. 2 is an exploded perspective view of the rotor assembly and
tube rotating apparatus shown in FIG. 1;
FIG. 3 is a detailed view of the tube rotating apparatus shown in
FIG. 1;
FIG. 4 is a top plan view of a cam used in the tube rotating
apparatus shown in FIG. 1;
FIG. 5 is a detailed cross-sectional view of the cam taken along
line 5--5 in FIG. 4;
FIG. 6 is a detailed cross-sectional view of the cam taken along
line 6--6 in FIG. 4;
FIG. 7 is a detailed cross-sectional view of the cam and block of
the tube rotating apparatus as taken along line 7--7 in FIG. 3;
FIG. 8 is a schematic view of the components of an exemplary
blood
centrifuge apparatus in which the rotor assembly shown in FIG. 1
can be employed;
FIGS. 9 and 10 are detailed views illustrating movement of the cam
follower and cam in response to movement of the block of the tube
rotating apparatus shown in FIG. 1;
FIG. 11 is a perspective view of a rotor assembly including a tube
rotating apparatus according to another embodiment of the present
invention;
FIG. 12 is a detailed cross-sectional view taken along line 12--12
in FIG. 11; and
FIGS. 13-17 are detailed views illustrating rotation of a carrier
tube as effected by the tube rotating apparatus of the rotor
assembly shown in FIG. 11.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A rotor assembly 100 in which a tube rotator assembly 102 according
to an embodiment of the present invention is employed is shown in
FIG. 1. The rotor assembly 100 can be included in a centrifuge
apparatus (not shown), such as that described in the aforementioned
copending U.S. patent application of Michael R. Walters entitled
"Inertial Tube Indexer and Method for Using the Same", Ser. No.
09/032,931, and in the aforementioned copending U.S. patent
application of Bradley S. Thomas et al. entitled "Blood
Centrifugation Device with Movable Optical Reader", Ser. No.
09/033,368, to centrifuge a blood or other fluid sample that has
been collected in a fluid tube 104, such as the type described in
the Background section above.
The rotor assembly 100 includes a rotor 106, which can be made of
metal, composite material, or any other suitable material, having a
planar or substantially planar surface 108 and an edge 110 which
extends along the circumference of the rotor 106 upwardly from the
planar surface 108. The rotor assembly 100 further includes a tube
receiving apparatus 112 which is adapted to receive one end of a
fluid tube 104 which is loaded in the rotor assembly 100.
The tube receiving apparatus 112 includes a receptacle 114 having a
recess therein into which is received one end of the fluid tube
104. Receptacle 114 can include a rubber washer or any other
suitable component which assists in holding the end of fluid tube
104 in the receptacle 114. Receptacle 114 is connected to a shaft
116, which is slidably and rotatably mounted to a shaft mounting
block 118 that is integral with or mechanically coupled to the
planar surface 108 of the rotor 106. A spring 120 is fitted over
the shaft 116, so that one end of the spring 120 contacts the
receptacle 114 and the other end of the spring 120 contacts shaft
mounting block 118. Accordingly, the spring 120 urges the
receptacle 114 in the direction indicated by arrow A to secure the
fluid tube 104 in a manner described in more detail below. Further
details of a rotor 106 and tube receiving apparatus 112 of the type
described above can be found in copending U.S. patent application
Ser. Nos. 09/032,931 and 09/033,368, cited above.
As shown in FIG. 1 and in more detail in FIGS. 2 and 3, the tube
rotator assembly 102 includes a block 122 which is slidably coupled
to the edge 110 of rotor 106 by block pins 124 and 126. That is,
block pins 124 and 126 pass through openings 128 and 130 in the
edge 110 of rotor 106, and through block openings 132 and 134 in
block 122. Block opening 132 has a large diameter portion 136 and a
small diameter portion 138 which form a step portion 140
therebetween, and block opening 134 also has a large diameter
portion 142 and a small diameter portion 144 which form a step
portion 146 therebetween.
Springs 148 and 150 are fitted about block pins 124 and 126 before
block pins 124 and 126 are inserted into openings 132 and 134,
respectively, but after pins 124 and 126 have passed through
openings 128 and 130, respectively. Hence, springs 148 and 150 are
maintained between the inner surface of edge 110 and their
respective step portions 140 and 146, and urge block 122 in a
direction indicated by arrow B in FIG. 3 for purposes described in
more detail below. Fasteners 152 and 154 are coupled to block pins
124 and 126, respectively, and prevent block 122 from traveling off
the distal ends of block pins 124 and 126.
Tube rotator assembly 102 further includes a cylindrical cam 156
which is rotatably coupled to edge 110 of rotor 106 by a cam pin
158 as shown. Cam pin 158 passes through opening 160 in edge 110,
and is received into opening 162 of cam 156. Cam pin 158 is
rotatable with respect to edge 110, thus enabling cam 156 to rotate
in the manner described below.
Cam 156 is received into a cam opening 164 in block 122 when block
122 is secured to the edge 110 of rotor 106 by block pins 124 and
126 as described above. Cam 156 is enable to rotate freely in cam
opening 164, which passes entirely through block 122 as shown. The
end of cam 156 opposite to that into which cam pin 158 is received
includes or is attached to a tube receptacle 166. Tube receptacle
166 includes an opening for receiving the end of fluid tube 104
opposite to the end which is received in receptacle 114 as
described above. Like receptacle 114, tube receptacle 166 can
include a rubber washer or any other suitable component which
assists in holding the end of fluid tube 104 in the receptacle 166.
Although receptacles 114 and 166 are shown as receiving a
capillary-type fluid tube 104, fluid tube 104 can also be a carrier
tube of the type described in the aforementioned copending U.S.
patent application of Edward G. King et al. entitled "Disposable
Blood Tube Holder and Method for Using the Same", Ser. No.
09/033,373.
Cam 156 further includes a cam groove pattern 168 disposed about
its circumference. As shown in more detail in FIG. 4, the cam
groove pattern includes a plurality of first longitudinal groove
sections 170-1, 170-2 through 170-n disposed at equal intervals
about the circumference of cam 156, and a plurality of second
longitudinal groove sections 172-1, 172-2 through 172-n disposed at
equal intervals about the circumference of cam 156. The first
groove sections and second groove sections are staggered on offset
with regard to each other about the circumference of the cam 156 as
shown. In this example, cam 156 includes eight first groove
sections 170-1 through 170-8, which are disposed at 45.degree.
intervals about the circumference of cam 156. Cam 156 also includes
eight second groove sections 172-1 through 172-8, which are
disposed at 45.degree. intervals about the circumference of cam
156. In this example, cam 156 has an overall length of about 0.685
inches and an overall diameter of about 0.500 inches. Also, the
width of each of the first groove sections 170-1 through 170-8 and
of each of the second groove sections 172-1 through 172-8 is about
0.067 inches at the outer surface of the cam 156, and each of the
first groove sections 170-1 through 170-8 and second groove
sections 172-1 through 172-8 have a maximum depth of about 0.050
inches measured radially to the outer surface of the cam 156.
As shown in FIGS. 4 and 5, each first groove section 170-1 through
170-8 has a raised portion 176-1 through 176-8, respectively,
creating steps 176-1 through 176-8 between the first groove
sections 170-1 through 170-8 and their adjacent second groove
sections 172-1 through 172-8, respectively. The purpose of these
steps is described in more detail below. As shown in FIGS. 4 and 6,
each second groove section 172-1 through 172-8 has a raised portion
178-1 through 178-8, respectively, creating steps 180-1 through
180-8 between the second groove sections 172-1 through 172-8 and
their adjacent first groove sections 170-2 through 172-1,
respectively, again, the purpose of these steps is described in
more detail below.
Tube rotator assembly 102 further includes a cam follower 182,
which can be a pin, rivet, or the like having a shaft as shown, for
example, in FIG. 2. The shaft of cam follower 182 passes through a
cam follower opening 184 in block 122, which opens into cam opening
164 in block 122. A resilient member 186, such as a leaf spring or
the like, is attached to block 122 by a screw 188, rivet, or any
suitable member, to resiliently secure cam follower 182 in cam
follower opening 184 as shown. Resilient member 186 permits cam
follower 182 to slide radially of the cam 156 for purposes
described in detail below. As shown schematically in FIG. 7, cam
follower 182 is received in groove pattern 168 of cam 156, and thus
follows groove pattern 168 in the manner described below.
As discussed above, rotor assembly 100 can be employed in a
centrifuge apparatus (not shown), such as those described in
copending U.S. patent application Ser. Nos. 09/032,931 and
09/033,368, cited above. In such an apparatus, as shown
schematically in FIG. 8, rotor assembly 100 is rotated about its
central axis by a motor 190 whose drive shaft is coupled to the
rotor assembly 100, and which is controlled by a computer or
central processing unit (CPU) 192.
As further illustrated, in FIG. 8, the centrifuge apparatus further
includes an optical carriage assembly 194 that includes a flash
tube assembly 196 having a flash tube 198 that is energized by a
flash lamp circuit 200 as controlled by the CPU 192. The optical
carriage assembly 194 further includes a CCD array assembly 202
having a CCD array 204. The CCD array 204 is controlled by a CCD
control board 206 that is controlled by CPU 192 to operate in
cooperation with flash tube 198, so that when flash tube 198 is
driven to emit light toward the fluid tube 104 loaded in the rotor
assembly 100, the CCD array 204 is controlled to detect light that
is produced or reflected by the contents (e.g., a blood fluid) of
the fluid tube 104 in response to the light emitted by the flash
tube 198.
The optical carriage assembly 194 further includes an optics
transport motor 208 which controls the movement of the optical
carriage assembly 194 and, in particular, the movement of the CCD
array assembly 202, along guide rails (not shown) in a direction
radial of the rotor assembly 100. The optics transport motor 208 is
controlled by CPU 192 to move the optical carriage assembly 194 in
this manner so that the CCD array 204 can read the entire sample
contained in the fluid tube 104.
The centrifuge apparatus also includes a rotor assembly orientation
sensor 210 which, as described in more detail below, senses when
the rotor assembly 100 is oriented such that the fluid tube 104 is
positioned below the CCD array 204, and provides a signal to CPU
192. When the CPU 192 receives the signal from the rotor assembly
orientation sensor 210, the CPU 192 controls the flash lamp circuit
200 to drive the flash tube 198, and controls the CCD control board
206 to control the CCD array 204 to read the light emitted from the
sample in the fluid tube 104.
The optical carriage assembly 194 further includes a filter rack
212 which is driven by a filter motor 214 to move in a direction
indicated by arrow C in FIG. 8, so that each of the individual
filters of the filter rack 212 can be positioned in front of the
CCD array 204 as desired. Each filter 214 in the filter rack 212 is
capable of filtering out light having particular wavelengths from
the light being emitted by the sample in fluid tube 104, while
allowing light of a desired wavelength to pass to the CCD array
204.
Additionally, the centrifuge apparatus 100 includes an LED bar 216
which is disposed below the rotor assembly 100 and is controlled by
CPU 192 via the drive board 218 to emit light in the direction of
rotor assembly 100. This light passes through slits (not shown) in
the rotor assembly 100, and is detected by CCD array 204 as the
rotor assembly 100 rotates, to ascertain the presence and absence
of a fluid tube 104 in the rotor assembly 100.
These and other features of a centrifuge apparatus in which the
rotor assembly 100 can be employed, as well as the operation of the
centrifuge apparatus as a whole, are described in more detail in
the aforementioned copending U.S. patent application Ser. Nos.
09/032,931 and 09/033,368, cited above, and in aforementioned
copending U.S. patent application of Bradley S. Thomas entitled
"Flash Tube Reflector with Arc Guide", Ser. No. 09/032,935.
The operation of tube rotator assembly 102 will now be described.
When a fluid tube 104 is ready for loading into the centrifuge
apparatus, the CPU 192 controls the motor 190 to rotate the rotor
assembly 100 to the proper orientation for loading of the fluid
tube 104, as determined through the use of the rotor assembly
orientation sensor 210 as described above. The fluid tube 104 is
then loaded into the rotor assembly 100 by placing one end of fluid
tube 104 into receptacle 114, and the other end of fluid tube 104
into receptacle 166. As discussed above, the shaft 116 attached to
receptacle 114 can be slid backward in the opening in shaft
mounting block 118 in order to load the fluid tube 104, and spring
120 urges receptacle 114 toward receptacle 166 so that the fluid
tube 104 is firmly held between the receptacles 114 and 166. A
rubber washer or the like in the receptacles 114 and 166 functions
to hold the ends of the tube 104 in the receptacles 114 and 166 as
discussed above.
After the fluid tube 104 containing the fluid (e.g., uncoagulated
blood) to be centrifuged is loaded into the rotor assembly 100 in
the manner described above, the centrifuge apparatus can begin to
centrifuge the sample to separate the components of the sample into
individual layers. The CPU 192 controls the motor 190 to rotate the
rotor assembly 100 at a suitable centrifuging speed, which is
typically about 8,000 r.p.m. to about 12,000 r.p.m. After the
sample has been centrifuged for the appropriate amount of time,
which is typically about 3 to 5 minutes, the centrifuged sample in
the capillary tube can be read by the optics in the optical
carriage assembly 194 as described in copending U.S. patent
application Ser. Nos. 09/032,931 and 09/033,368, cited above. The
CPU 192 will typically decrease the rotation speed of the rotor
assembly 100 to a suitable speed for reading, which is usually
about 1,000-2,500 r.p.m. However, the centrifuging speed and the
reading speed can be varied as necessary to suit the requirements
of particular applications.
Also, as can be appreciated from the following, when the rotor
assembly 100 is rotated at the centrifuging speed, block 122 is
moved by centrifugal force in the direction of arrow D in FIG. 3
until it abuts against the inner surface of the edge 110 of rotor
106. Block 122 remains abutted against the edge 110 of the rotor
106 until the speed of rotation of the rotor 106 is decreased to a
level at which the centrifugal force imposed on block 122 decreases
to a magnitude at which the force imposed on block 122 by springs
148 and 150 moves block 122 in the direction of arrow B in FIG. 3
back to its original position. This movement of block 122 results
in the fluid tube 104 being rotated or "indexed" by one indexing
increment, as will now be described.
After the appropriate number of readings have been taken of the
sample by the CCD array 204 of the optical carriage assembly 194
when the fluid tube 104 is in its initial reading orientation in
the rotor assembly 100 (i.e., after the initial "indexing" has been
performed when the speed of the rotor 106 is increased for
centrifugation and decreased for reading as described above), the
CPU 192 will control the motor in such a manner that the tube
rotator assembly 102 rotates the fluid tube 104 incrementally about
its longitudinal axis so that readings of the sample can be taken
from different locations about the circumference of the fluid tube
104. As described above in the Background section, it is desirable
to take sample readings at different locations about the
circumference of the fluid tube 104 (i.e., with the fluid tube 104
at different orientations about its longitudinal axis) to obtain
more accurate measurements of the lengths of the layers in the
centrifuged blood sample. The CPU 192 will therefore control the
tube rotator assembly 102 to perform this incremental rotation or
"indexing" of the fluid tube 104 by changing the rotational speed
of the motor 190.
Specifically, during reading, the motor 190 normally rotates the
rotor assembly 100 in a given direction (e.g., counterclockwise) at
a suitable speed as discussed above. At this rotational speed, the
centrifugal force imposed on block 122 by the rotation of rotor
assembly 100 in the direction indicated by arrow D in FIG. 3 is
insufficient to overcome the force imposed on block 122 by springs
148 and 150 in the direction of arrow B in FIG. 3. Accordingly,
block 122 remains positioned with respect to cam 156 as indicated
in FIG. 3, with the cam follower 182 being positioned in the groove
pattern 168 the solid line position shown in FIG. 9. That is, cam
follower 182 remains near the proximal end of one of the first
groove sections (in this example, first groove section 170-1). A
reading or multiple readings of the centrifuged sample in the fluid
tube 104 can be taken, if desired, before any rotating or
"indexing" of the
fluid tube 104 is performed for reading purposes.
When it becomes appropriate to rotate or "index" fluid tube 104
about its longitudinal axis, CPU 192 controls motor 190 to increase
its rotational speed, which in turn increases the rotational speed
of the rotor assembly 100. This increased rotational speed of the
rotor assembly 102 imposes a greater centrifugal force on block 122
in the direction of arrow D in FIG. 3. Once the rotational speed
becomes large enough, the centrifugal force imposed on block 122
overcomes the force imposed on block 122 by springs 148 and 150,
and moves block 122 along block pins 124 and 126 in the direction
indicated by arrow D.
The rotational speed at which the spring force is overcome can be
any suitable speed, such as 8,000-10,000 r.p.m., or more or less,
and is dependent on the mass of block 122 and the spring force of
springs 148 and 150. That is, by decreasing the spring force of
springs 148 and 150, increasing the mass of block 122, or both, the
rotational speed at which the centrifugal force overcomes the
spring force is decreased. Alternatively, by increasing the spring
force of springs 148 and 150, decreasing the mass of block 122, or
both, the rotational speed at which the centrifugal force overcomes
the spring force is increased.
When block 122 moves in the direction indicated by arrow D, cam
follower 182 also moves in the direction of arrow D. As shown in
FIG. 9, when cam follower 182 moves in the direction of arrow D in
first groove section 170-1, it abuts against step 180-8 as shown in
dashed line. Step 180-8 prevents cam follower 182 from entering
second groove section 172-8, and directs cam follower to follow
wall 220-1 forming a portion of first groove section 170-1.
Cam follower 182 is mounted in block 122, and is thus prevented
from moving in a direction transverse of arrow D. Hence, cam
follower 182 imposes a force on step 180-8, and subsequently on the
wall 220-1. Because cam 156 is rotatable about cam pin 158 as
described above, the force imposed on step 180-8 and wall 220-1 by
cam follower 182 is translated into a rotational force which
rotates cam 156 in the direction indicated by arrow E in FIGS. 7
and 9. This rotation of cam 156 allows cam follower 182 to follow
first groove section 170-1 into second groove section 172-1, where
it becomes positioned as shown in dashed lines in FIG. 9 and by
solid line in FIG. 10. Because resilient member 186 allows cam
follower 182 to deflect radially of the cam 156, cam follower 182
can travel along raised portion 174-1 essentially without
restriction. As cam follower 182 follows raised portion 174-1 of
first groove portion 170-1 and passes over step 176-1 into second
groove section 172-1, the cam 156 is thus rotated by 22.5.degree.,
which is one-half of the spacing interval between adjacent first
groove sections 170-1 and 170-2, which in this example is
45.degree.. Accordingly, the cam 156 rotates fluid tube 104 by
22.5.degree. about its longitudinal axis.
To rotate the fluid tube 104 by one complete indexing increment
which, in this example, is 45.degree., the CPU 192 next slows the
speed of rotation of motor 190 and thus, the rotation of rotor
assembly 100, down to a speed at which reading is performed (about
1,000-2,500 r.p.m. in this example). When this occurs, the
centrifugal force imposed on block 122 due to the rotation of rotor
assembly 100 decreases to a level at which it is overcome by the
force imposed on block 122 by springs 148 and 150. When this
occurs, the spring force urges block 122 in the direction indicated
by arrow B in FIGS. 3 and 10.
When block 122 moves in the direction indicated by arrow B, cam
follower 182 also moves in the direction of arrow B. As shown in
FIG. 10, when cam follower 182 moves in the direction of arrow B in
second groove section 172-1, it abuts against step 176-1 as shown
in dashed lines. Step 176-1 prevents cam follower 182 from entering
first groove section 170-1, and directs cam follower 182 to follow
wall 222-1 forming a portion of second groove section 172-1.
Cam follower 182 is mounted in block 122, and is thus prevented
from moving in a direction transverse of arrow B. Hence, cam
follower 182 imposes a force on step 176-1, and subsequently on
wall 222-1. Because cam 156 is rotatable about cam pin 158 as
described above, the force imposed on step 176-1 and wall 222-1 by
cam follower 182 is translated into a rotational force which
rotates cam 156 in the direction indicated by arrow E in FIG. 10.
This rotation of cam 156 allows cam follower 182 to follow second
groove section 172-1 into first groove section 170-2, where it
becomes positioned as shown in dotted line in FIG. 10. As cam
follower 182 follows raised portion 178-1 of second groove portion
172-1 and passes over step 180-1 into first groove section 172-2,
the cam 156 is thus rotated by 22.5.degree., which is one-half of
the interval spacing between adjacent first groove sections 170-1
and 170-2, which in this example is 45.degree.. Accordingly, the
cam 156 rotates fluid tube 104 by another 22.5.degree. about its
longitudinal axis.
After completion of the above operation, cam follower 182 has moved
from the distal end of first groove section 170-1 to the distal end
of first groove section 170-2, and cam 156 and fluid tube 104 have
been rotated about their respectively longitudinal axes by
45.degree., which in this example is one indexing increment.
Readings of the centrifuged sample contained in fluid tube 104 can
then be taken with the fluid tube 104 in this new orientation in
the manner described above.
After all readings at this orientation have been taken, the above
indexing process can be repeated to index the fluid tube 104 by six
additional indexing increments if readings were taken prior to any
indexing being performed for reading purposes (i.e., not counting
the initial indexing that occurs when the rotor speed is increased
to centrifuge the sample, and then decreased to the reading speed),
with readings being taken after each indexing increment. That is,
if readings were taken before any indexing was performed for
reading purposes, the indexing is performed a total of seven times,
with the fluid tube 104 being rotated a total of 315.degree. from
the position at which the first readings were taken. However, if no
readings were taken before the first indexing for reading purposes
is performed, the indexing is performed a total of eight times,
with the fluid tube 104 being rotated a total of 360.degree. from
the position prior to indexing for reading, and the last readings
being taken after the fluid tube 104 has been indexed the eighth
time.
The tube rotator assembly 102 is not limited to the configuration
described above. For example, as shown in FIGS. 11 and 12, the tube
rotator assembly can be configured as an indexing apparatus which
rotates a fluid tube in the form of a carrier tube 224 as described
in copending U.S. patent application Ser. No. 09/033,37 cited
above. The carrier tube 224 includes a fluid tube therein which
contains a sample to be centrifuged. In this example, rotor
assembly 226 includes a rotor 228 and a hub assembly 230 which
couples the rotor assembly 226 to the shaft of the motor 190, and
is also rotatable in a restricted manner with respect to the rotor
228. The hub assembly 230 includes the indexing apparatus 232,
which comprises a pivotable member 234 that is adapted to engage a
gear 236 present on the cap 238 of carrier tube 224.
During normal rotation of the rotor assembly 226, the hub assembly
230 and rotor 228 rotate in unison. Indexing of the carrier tube
224 is performed by abruptly slowing the speed of rotation of the
motor 190, so that the rotor 228 is permitted to rotate with
respect to the hub assembly 230. As shown in FIGS. 13-15, the
rotation of the rotor 228 with respect to the hub assembly 230
causes the pivotable member 234 to engage a tooth 240 of gear 236
to rotate the gear 236 and thus, rotate the carrier tube 224 about
its longitudinal axis in a direction RI. The pivotable member 234
is reset to the pre-indexing position as shown in FIGS. 15-17 when
the speed of rotation of the motor 190 is resumed so that the hub
assembly 230 and rotor 228 again rotate in unison. Readings of the
sample contained in the fluid tube present in carrier tube 224 can
be taken at each indexing interval. Further details of the rotor
assembly and indexing apparatus, the manner in which reading is
performed, and the overall operation of the centrifuge device
including a rotor assembly of this type, are disclosed in U.S.
patent application Ser. No. 09/032,931, cited above.
Although only certain exemplary embodiments of this invention have
been described in detail above, those skilled in the art will
readily appreciate that many modifications are possible in the
exemplary embodiments without materially departing from the novel
teachings and advantages of this invention. Accordingly, all such
modifications are intended to be included within the scope of this
invention as defined in the following claims.
* * * * *